Friday, January 20, 2012

Simultaneously Mitigating Near-Term Climate Change and Improving Human Health and Food Security
A new study led by [Drew Shindell of NASA's Goddard Institute for Space Studies (GISS) in New York City], highlights 14 key air pollution control measures that, if implemented, could slow the pace of global warming, improve health and boost agricultural production.

The research ... finds that focusing on these measures could slow mean global warming 0.9 ºF (0.5ºC) by 2050, increase global crop yields by up to 135 million metric tons per season and prevent hundreds of thousands of premature deaths each year. While all regions of the world would benefit, countries in Asia and the Middle East would see the biggest health and agricultural gains from emissions reductions.
Shindell and an international team considered about 400 control measures based on technologies evaluated by the International Institute for Applied Systems Analysis in Laxenburg, Austria. The new study focused on 14 measures with the greatest climate benefit. All 14 would curb the release of either black carbon or methane, pollutants that exacerbate climate change and damage human or plant health either directly or by leading to ozone formation.

Shindell and his team concluded that these control measures would provide the greatest protection against global warming to Russia, Tajikistan and Kyrgyzstan, countries with large areas of snow or ice cover. Iran, Pakistan and Jordan would experience the most improvement in agricultural production. Southern Asia and the Sahel region of Africa would see the most beneficial changes to precipitation patterns.

The south Asian countries of India, Bangladesh and Nepal would see the biggest reductions in premature deaths. The study estimates that globally between 700,000 and 4.7 million premature deaths could be prevented each year.

Black carbon and methane have many sources. Reducing emissions would require that societies make multiple infrastructure upgrades. For methane, the key strategies the scientists considered were capturing gas escaping from coal mines and oil and natural gas facilities, as well as reducing leakage from long-distance pipelines, preventing emissions from city landfills, updating wastewater treatment plants, aerating rice paddies more, and limiting emissions from manure on farms.

For black carbon, the strategies analyzed include installing filters in diesel vehicles, keeping high-emitting vehicles off the road, upgrading cooking stoves and boilers to cleaner burning types, installing more efficient kilns for brick production, upgrading coke ovens and banning agricultural burning.

The scientists used computer models developed at GISS and the Max Planck Institute for Meteorology in Hamburg, Germany, to model the impact of emissions reductions. The models showed widespread benefits from the methane reduction because it is evenly distributed throughout the atmosphere. Black carbon falls out of the atmosphere after a few days so the benefits are stronger in certain regions, especially ones with large amounts of snow and ice.

... The new study builds on a United Nations Environment Program/World Meteorological Organization report, also led by Shindell, published last year.
Abstract: Tropospheric ozone and black carbon (BC) contribute to both degraded air quality and global warming. We considered ~400 emission control measures to reduce these pollutants by using current technology and experience. We identified 14 measures targeting methane and BC emissions that reduce projected global mean warming ~0.5°C by 2050. This strategy avoids 0.7 to 4.7 million annual premature deaths from outdoor air pollution and increases annual crop yields by 30 to 135 million metric tons due to ozone reductions in 2030 and beyond. Benefits of methane emissions reductions are valued at $700 to $5,000 per metric ton, which is well above typical marginal abatement costs (less than $250). The selected controls target different sources and influence climate on shorter time scales than those of carbon dioxide–reduction measures. Implementing both substantially reduces the risks of crossing the 2°C threshold.
A 2007 Stanford University study calculated that carbon dioxide was the No. 1 cause of man-made global warming, accounting for 48 percent of the problem. Soot was second with 16 percent of the warming and methane was right behind at 14 percent.  But over a 20-year period, a molecule of methane or soot causes substantially more warming then a carbon dioxide molecule.

The new research won wide praise from outside scientists, including a conservative researcher who held a top post in the George W. Bush administration.

"So rather than focusing only on carbon dioxide emissions, where we have to make a tradeoff with energy prices, this strategy focuses on 'win-win-win' pathways that have benefits to human health, agriculture and stabilizing the Earth's climate," said University of Minnesota ecology professor Jonathan Foley, who wasn't part of the study. "That's brilliant."

John D. Graham, who oversaw regulations at the Office of Management and Budget in the Bush administration and is now dean of public and environmental affairs at Indiana University, said: "This is an important study that deserves serious consideration by policy makers as well as scientists."

The study even does a cost-benefit analysis to see if these pollution control methods are too expensive to be anything but fantasy. They actually pay off with benefits that are as much as ten times the value of the costs, Shindell said. The paper calculates that as of 2030, the pollution reduction methods would bring about $6.5 trillion in annual benefits from fewer people dying from air pollution, less global warming and increased crop production.

In the United States, Shindell calculates the measures would prevent about 14,000 air pollution deaths in people older than 30 by the year 2030. About 0.8 degrees Fahrenheit of projected warming in the U.S. would be prevented by 2050.

But health benefits would be far bigger in China and India where soot is more of a problem.

The study comes a day after the U.S. Environmental Protection Agency released the most detailed data yet on American greenhouse gas emissions. Of the emissions reported to the government, nearly three-quarters came from power plants. But with methane, it's different. Nineteen of the top 20 methane emitters were landfills.

Stanford University climate scientist Chris Field, who is a leader in the Intergovernmental Panel on Climate Change but wasn't part of this study, praised the study but said he worried that officials would delay cutting back on the more prevalent carbon dioxide. Focusing solely on methane and soot and ignoring carbon dioxide "tends to exacerbate climate change," he said.

Also see:

by Drew Shindell 1,*, Johan C. I. Kuylenstierna 2, Elisabetta Vignati 3, Rita van Dingenen 3, Markus Amann 4, Zbigniew Klimont 4, Susan C. Anenberg 5, Nicholas Muller 6, Greet Janssens-Maenhout 3,  Frank Raes 3, Joel Schwartz 7, Greg Faluvegi 1, Luca Pozzoli 3,†, Kaarle Kupiainen 4, Lena Höglund-Isaksson 4, Lisa Emberson 2, David Streets 8, V. Ramanathan 9, Kevin Hicks 2, N. T. Kim Oanh 10, George Milly 1, Martin Williams 11, Volodymyr Demkine 12 and David Fowler 13
1. NASA Goddard Institute for Space Studies and Columbia Earth Institute, Columbia University, New York, NY 10025, USA.
2. Stockholm Environment Institute, Environment Department, University of York, York YO10 5DD, UK.
3. Joint Research Centre of the European Commission, Ispra 21027, Italy.
4. International Institute for Applied Systems Analysis, Laxenburg A-2361, Austria.
5. U.S. Environmental Protection Agency, Washington, DC 20460, USA.
6. Department of Economics, Middlebury College, Middlebury, VT 05753, USA.
7. Department of Environmental Health, Harvard School of Public Health, Boston, MA 02215, USA.
8. Argonne National Laboratory, Argonne, IL 60439, USA.
9. Scripps Institute of Oceanography, University of California, San Diego, San Diego, CA 92093, USA.
10. Asian Institute of Technology, Bangkok 10400, Thailand.
11. Environmental Research Group, King’s College London, London SE1 9NH, UK.
12. United Nations Environment Programme (UNEP), Nairobi 00100, Kenya.
13. Center for Ecology and Hydrology, Midlothian EH26 0QB, UK.
† Present address: Eurasia Institute of Earth Sciences, Istanbul Technical University, Istanbul 34469, Turkey.
* To whom correspondence should be addressed. E-mail:
Volume 335, Number 6065; January 13, 2012: pages 183-189

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